Sustainable CO 2 conversion over plasmonic RuO composites via artificial photosynthesis Eva Naughton a , Ravindranathan Thampi b and James A. Sullivan a a UCD School of Chemistry, Belfield, Dublin 4, Ireland, b UCD School of Chemical and Bioprocess Engineering, Belfield, Dublin 4, Ireland eva.naughton@ucdconnect.ie 2 -containing Since the industrial revolution fossil fuels have driven economic growth and now , approximately 85% of global energy generation comes from combustion of coal, oil, or natural gas 1 . However, temperature increases due to rising CO 2 concentrations are projected to have many negative impacts, and therefore scientists are looking for methods to tackle this increase in CO 2 . One method is the artificial photosynthesis (AP) reaction. Reacting CO 2 with H 2 O to form CO or hydrocarbons using a sustainable energy source has become hugely desirable. The success of this process would contribute to the goal of creating a circular carbon economy and would ameliorate effects of fossil fuel use. Certain metals or conducting metal oxides can interact with UV or visible photons to give rise to excitation known as surface plasmon resonance, the oscillation of free electrons on the surface of a metal or metallic particle. These plasmons can decay via the generation of catalytically useful high energy “hot electrons”. Plasmonic nanostructures can act as co-catalysts with semiconductors, speeding up the transfer of excited electrons to acceptor molecules (either directly transferring “hot electrons” to the acceptor, or first injecting the electron into the CB of the semiconductor) and suppressing charge recombination, thereby increasing catalytic efficiency 2 . RuO 2 , a plasmonic nanostructure, coupled with TiO 2 , a UV-absorbing semiconductor, has shown to be active in the AP reaction, but neither component alone possessed the ability to both reduce CO 2 and oxidise H 2 O under visible light 3 . In this study RuO 2 was prepared on the surfaces of GaP (a CO 2 reducing catalyst) and Fe 2 O 3 (a H 2 O oxidising catalyst). The effect of the band edge positions of the semiconductors coupled with RuO 2 in the AP reaction will be examined and used to help determine a mechanism of reaction.
Fig 1: Proposed origin of the synergy between RuO 2 and TiO 2 in the AP reaction
3 (left), and band positions of Fe
2 O 3 and GaP
relative to the energy levels of the redox couples involved in AP (right). This submission has been supported by funding from Science Foundation Ireland under grant number 16/RC/3889 and is co- funded under the European Regional Development Fund & by BiOrbic industry partners. References 1. B. Zhang and L. Sun, Chemical Society Reviews , 2019, 48 , 2216-2264. 2. X. Zhang, Y. L. Chen, R.-S. Liu and D. P. Tsai, Reports on Progress in Physics , 2013, 76 , 046401-046401. 3. E. Morais, C. O'Modhrain, K. R. Thampi and J. A. Sullivan, Journal of Catalysis , 2021, 401 , 288-296.
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